Starch manufacturing process



May 5, 1936- A. PELTZER, JR 'n 2,039,605

STARCH MANUFACTURING PROCESS Filed July 31, 1933 ATTORN Patented May 5,1936 UNITED STATES PATENT oFFicE SVTARCH MANUFACTURING PROCESS AlbertPeltzer, Jr., Palo Alto, Calif., assigner Merco Centrifugal SeparatorCo. Ltd., San Francisco, Calif., a corporation of California ApplicationJuly 31, 1933, SerialNo. 682,909 'z claims. (01.'12'1-69)l Thisinvention applies generally to systems for the manufacture of starchfrom materials like corn, where the corn orI like material isdisintegrated and components such as germs, hulls,

vfibrous material and gluten, are removed from the desired starch.

It is an object of the invention to provide an improved process ormethod for the removal of gluten from wet starch bearing feed materialsuch as is produced in systems of the above character, thereby makingpossible the manufacture of starch having a relatively low proteincontent. In carrying out my invention a step of flotation separation isutilized, and this step is made effective by the prior removal offibrous material. Furthermore foaming or frothing is accomplished in aseparating step prior to flotation, and simultaneously withremoval offibrous material.

Further objects and features of the invention will appear from thefollowing description in which the preferred embodiments of theinvention are set forth in detailin conjunction with the accompanyingdrawing.

' Referring to the drawing:

Figure 1 is a diagrammatic view showing one way in which my process maybe carried out in practice.

Fig. 2 is a diagrammatic view showing a modiiied manner for carrying outthe process.

'Ihe process or method of the present invention in its preferred formcan be outlined briefly as comprising subjecting wet starch bearingmaterial to centrifugal separation, in such a manner that fibrousmaterial therein passes out with the gluten overflow, and the starchunderow is foamed or frothed to a substantial degree. Further removal ofgluten from this starch underilow is then accomplished by flotation.

The process can be better understood after a brief description of thedrawing. Referring first to Fig. 1, I have indicated a centrifuge of thetype disclosed in copending application Serial No. 586,773, filedJanuary 13, 1932. A centrifuge of this character is characterized by thefact that it operates continuously, and a portion of the underflow iscontinually returned to the centrifuge bowl adjacent the peripherythereof. Thus, in the diagrammatic representation the centriiuge bowl II is provided with a separating chamber I2 into which the wet starchbearing feed ma- 'terial is introduced as indicated by line I3. A starchunderflow discharges from peripheral nozzles I4 and is received byvolute I6, while a gluten overflow discharges over the wier I1. A majorpart of the material discharged from the nozzles I 4, after furtherremovalof gluten therefrom as will be presently explained, isycontinuously returned back into the centrifuge chamber as indicated byline I8. The material returned to the centrifuge rotor by way of line I8is delivered 5 into the bowl at a point adjacent the periphery thereof,thru an impeller 20.

Wash liquor can be introduced into the rotor together with the return,as indicated byline I9. The use of a ltrate obtained rom otherV points10 in the'wet starch system is desirable, since such a ltrate promotesfoaming.

With a centrifuge of the type described above, Where the feed materialconsists chiefly of starch together with gluten and fibrous material(com- 15 monly termed mill starch), the overiiow consists of glutentogether with fibrous material from the feed. The underflow received bythe volute I6 consists of starch which still retains a part of thegluten from the feed, but which will be sub'- 20 i 'underow will befoamed or frothed to a substantial extent. Thisv foaming action isattributed 25 to the entrance of air or other gases with the feed, andto introduction of air into the return circuit because of `letting intovolute I8, and the beating and violent agitation to which the materialis subjected. I have found that the foamed 30 or frothed condition ofthe underflow facilitates a subsequent separation oi' remaining glutenfrom the starch, by flotation. Thus as shown in Fig. 1, the starchunderflow removed from volute IS is introduced into a vessel 22 by wayoi pipe 2|. 35 Gluten separated from the starch in vessel 22 is floatedoff over wier 23, while the starch is removed by way of stand pipe 2dand outflow box 26. A rotating skimmer 2l can be employed axljacent towier 23, to secure more effective removal 4o of the gluten. A continuousreturn of starch to the centrifuge is afforded by pipe Ilia, which is anextension of line I8. Suitable bathing can be provided for the dischargefrom pipe 2| and the inlet end of pipe I8a, as illustrated. 45

The removal of gluten from the underflow by flotation has been found tobe highly eective. The substantial absence of fibrous material in thecentrifuge underflow eliminates a middle draw-off from the notationstep, thus making 50 possible continuous operation with eflicientseparation of gluten, and avoiding starch losses and practicaldifficulties which a draw-od of midlings would occasion. Since in thisinstance the step of notation is interposed in the return ir- 55cuit,'the material returned by4 way of line I8 is 'largely freed ofgluten, and is substantially un-v In'Fig. 2 I have shown a modifiedmanner lin which the step of flotation is associated with thecentrifugal separation. In this case the return of a major part of theunderflow received by volute Il occurs directly within the centrifugemachine' -by way'of line Il, while a part of this foamed underflow isdiverted thru pipe 2l for otation. Such an arrangement does not subjectthe underflow to flotation before being returned to the centrifuge, butit enables variations in the underflow to be immediately reflected invariations in the return, thus affording better inherent stability.

I claim:

l. In a process of the character ,described for the production of starchfrom wet starch bear-` ing feed material containing gluten and fibrouss,

material, the steps of centrifugally separating the feed into a starchunderflow and a gluten overow containing the majority of the brousmaterial from the feed, yand then subjecting the underow t flotation forthe further removal of gluten.

2. In a process of the character described for the production of starchfrom wet starch bearing feed material containing gluten, the steps ofremoving a gluten overilow from the feed material by centrifugalseparation while simultaneously frothing the starch underflow, and thenseparating further gluten from the frothed starch underilow byflotation.

3. In a process of the character described for the production of starchfrom starch `bearing feed material containing gluten and fibrousmaterial, the steps of centrifugally separating the feed into afrothedstarch underflow and a gluten overow containing the majority of thefibrous material from the feed, and subjecting the frothed underflow toflotation for the further removal of gluten.

4. In a process of the character described for the production of starchfrom wet starch bearing' feed material containing gluten and fibrous.materiaL the stepsof centrifugally separating trifugal separation, andseparating further glutenA from the underflow by flotation.

5. In a process of the character described for the production of starchfrom'wet starch bearing feed material containing gluteny and fibrousmaterial, the steps of separating the feed into a starch underflow and agluten overflow containlng a. majority :of the fibrous material, bycentrifuging, said centrifuging being characterized by the continuousreturn of a portion of the underilowback to the zone of separation, and

being also characterized by a frothing of the underflow, and effectingfurther removal of gluten from the underflow by flotation.

6. In a process of the character` described for effecting Separationbetween starch and gluten in wet starch bearing material-like millstarch, centrifuging ythe mill starch to form a frothed starch underflowand a gluten overflow, directly delivering the frothed underflow to abody of the same where the frothed component thereof'is floatedv oil',continuously returning defrothed starch from' said body to saidcentrifuging operation, and removing' starch from said body for nnaidelivery at a rate substantially less than the 1 rate of return. y Y

7. In a .processof the character described for thetreatment of millstarch or like starch bearing material containing ilbrous materialtogether with starch' and gluten, centrifuging .the mill starch to forma. frothed starch 'underflow and la gluten overflow which containssubstantially all of the fibrous material, directly delivering thefrothed 4underflow to abody of the same where the frothed glutencomponent thereof is floated off, continuously returning defrothedstarch from said bodyto said centrifuging operation, and removing starchfrom saidv body for final delivery at a rate substantially less than therate of return. 1

ALBERT PELTZER, Jn.

